Preheat oven to 350 °. Spray a cookie sheet with non stick spray.
Whisk together flour, baking powder, baking soda, salt, and spices in a small bowl; set aside.
Beat softened butter and sugar in a large mixing bowl till creamy. Beat in pumpkin, egg, and vanilla. Stir in dry ingredients just until moistened.
Scoop spoonfuls of dough onto prepared pans. Flatten slightly with a set hand or spoon. Bake at 350° for 13-18 minutes or till set in the middle.
Let cookies cool completely, then drizzle icing over the tops. I like to use a ziplock bag with the corner snipped to drizzle my icing, but you can just use a fork or spoon.
For icing, whisk all ingredients together until smooth, adding enough milk to get the correct consistency.